m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  Sorry for the triple post here, but this G-Sync support over HDMI in order to operate with these LG TVs came as news to me.  Detailed technical information seems to be scarce, but the articles I've read indicate that a) you are supposed to use the HDMI output on your GPU to use G-Sync with these TVs, and b) this capability is only available with RTX GPUs and GTX 16 Series GPUs.  That's interesting for two reasons.

First, G-Sync in the past only worked over DisplayPort and required the display to have a proprietary G-Sync control board containing pretty powerful components.  Additionally, second, G-Sync has been supported on GeForce GPUs going back well before the RTX and GTX 16 Series GPUs.

So my GUESS here is that the G-Sync in this particular case of the LG OLED TVs isn't the "normal G-Sync" that involves NVIDIA proprietary technology, but rather HDMI VRR or something very much like it.  That might explain both why this LG OLED use case works over HDMI and why it's only possible on NVIDIA's latest GPUs.  But that may also mean that G-Sync to an LG OLED might be possible ONLY from an actual HDMI source port wired directly to the NVIDIA GPU, i.e. the Mini-DisplayPort output might not be usable for G-Sync to an LG OLED TV no matter what type of adapter/cable you use.  So hopefully your HDMI output is wired to the NVIDIA GPU.

As for the 240 Hz display you're considering purchasing, if it supports G-Sync, chances are it will be "normal G-Sync" that operates over DisplayPort, in which case connect it to the Mini-DisplayPort output.

@Carl1978  Ok, building on the above, it appears that the 2019 LG OLED models are "G-Sync Compatible" displays, and since they appear not to have any DisplayPort inputs, it appears that NVIDIA has done something to get this running over HDMI.  In that case, if you run the test I mentioned above and find that your HDMI output is wired to your NVIDIA GPU (which seems likely on that system since Dell might have done that to support running HDMI-based VR headsets), then I'd connect via HDMI.  If not, then if you're trying to run high refresh rates, you might have to get an active Mini-DisplayPort to HDMI 2.0 adapter.  The less common passive Mini-DisplayPort to HDMI adapters and cables won't run HDMI 2.0, to my knowledge.  The issue with them is that they rely on the source DisplayPort output supporting "Dual Mode DisplayPort", which allows a DisplayPort output to fall back to native HDMI signaling.  The problem is that DisplayPort existed long before HDMI 2.0 did, so I don't know if that capability will allow the source to send (and therefore the adapter/cable to carry) an HDMI 2.0 signal.  By comparison, an active adapter involves the source system sending a native DisplayPort signal to the adapter and then the adapter converts it to HDMI 2.0.

Also, according to this NVIDIA article, you can only run 120 Hz when you're using QHD resolution.  With 4K you'd be limited to 60 Hz.  That's a limitation of HDMI 2.0 itself.  But that article might help you get everything set up.

@Carl1978  G-Sync has two key requirements.  First, you have to be using DisplayPort (or USB-C/TB3, which uses DisplayPort for video traffic).  And second, you have to be using a port that is wired directly to the system's NVIDIA GPU.  On every Dell system I've seen, the USB-C/TB3 port is wired to the Intel GPU, and the NVIDIA GPU only accelerates content on displays attached that way via NVIDIA Optimus, which means it acts as a "render-only" device that passes completed video frames to the Intel GPU.  That has some battery life advantages, but it prevents using G-Sync, as well as Adaptive V-Sync, VR, stereoscopic 3D, and some other technologies.

However, I believe on that system that the Mini-DP output is wired directly to the NVIDIA GPU, in which case that would be the preferable output.  If you want to verify, connect a display to whichever output(s) you want to test, then open NVIDIA Control Panel and go to the PhysX Configuration section.  In there you'll see a diagram showing which GPU controls each active display.  See how it looks when you have displays connected various ways.

Okay so this has become more interesting! :). 

https://gyazo.com/d73573a970bd22ea118e1251c0f7f833 - so I selected a 4k display, it then did something really funky and switched back to laptop/LG screens on at the same time, duplicate mode, but the laptop was all purple tinge.  Then I noticed the g-sync options appeared and was labelling the LG monitor differently, now it will allow me to select 4k at 60hz, but gsync is enabled so at least I will know that's working.  Just puzzled to why there isn't a 2k option better than 30hz...and quite amazed this is all working over hdmi so far.

https://gyazo.com/01c8e008012167a0f7d0517b8d78e367 here is the gsync options
if I have the laptop only this is the only resolution you can get https://gyazo.com/8f823e283bfbebe8b090b0733f1cb5fc

@Carl1978  Just saw that other screenshot too.  QHD (2560x1440) isn't even listed in your resolution choices, at least not within the portion of the list that's visible in your screenshot.  2560x1600 is, but that's not the same thing.  However, comparing that against the screenshot in the NVIDIA article I linked, 2560x1440 is at the very bottom in the PC resolution section, not the "UltraHD,HD,SD" section.  So maybe scroll down your resolution list to see if you have 2560x1440 at the very bottom somewhere.  And if you do, see if you can enable 120 Hz.

Hi again,

I've just noticed your reply again, thanks once more.  This is just a follow up on trying to get past 30fps, it was set on the laptop to 4k but in the game it was 1080p still, I adjusted to 4k, and also the 1440 on also, both were still on 30fps, id be happy to get the higher fps with a higher resolution on a 55 inch screen.  

I've not read your reply yet but I will first thing in the morning, I did see about g-sync and the 144hz, maybe it might have been a better option from that pov, that said with gsync working I'm guessing that's less of a problem as I dont intend to game just on the laptop screen itself.  The higher refresh was more for the sake of my eyes, can't explain why but higher refresh just seems to cause less eye fatigue.

Look forward to picking this up in the morning, appreciated again

@Carl1978  It seems you wrote another reply while I was posting my own.  I'm not sure why you're limited to 30 Hz when selecting QHD, particularly as the NVIDIA article I linked that specifically deals with your TV suggests that you should be able to run 120 Hz.  Maybe confirm you're running the latest firmware and NVIDIA drivers?

@Carl1978  Happy to help. I'll try to address some of your follow-up questions and clarify a few things:

Your screenshot: The screenshot you posted clearly shows the active external display (surprisingly) even the laptop's built-in display both controlled by the NVIDIA GPU.  I guess this system might be wired that way in order to support the G-Sync built-in display option it offers.  I'm not sure what you mean by saying you couldn't quite see the video card connections.  They're right there in that diagram.  But the important part is that the line from your display goes to the gray box that corresponds to your NVIDIA GPU.  And since there isn't even an Intel GPU shown at all, I suppose it's possible that even the USB-C/TB3 video output is wired to the NVIDIA GPU, although even if that's the case, it won't necessarily be any better -- in fact the specs indicate it may be worse.  According to Dell's product page, the USB-C/TB3 port only supports DisplayPort 1.2, whereas the Mini-DisplayPort output supports DisplayPort 1.4.  Of course whether that makes a practical difference depends on what display(s) you connect to those interfaces, but I wouldn't feel too disappointed about not being able to use USB-C/TB3.

G-Sync and your built-in display: The NVIDIA article I linked shows how to enable G-Sync.  If you successfully enable it as shown in that article, then it's working.  As for your built-in display, I would have gone with 144 Hz G-Sync rather than 300 Hz seeing as the latter seems not to allow G-Sync.  For one thing, whether the human eye can even detect anything beyond 144 Hz is dubious at best.  Even hardcore competitive gamers seem to find that 120 Hz is plenty.  But much more importantly, running a high refresh rate without the benefit of G-Sync can actually be a much worse experience overall.  The reason is that without G-Sync, your options are either V-Sync Off or V-Sync On.  Running V-Sync Off means you can experience frame tearing, since that's precisely what V-Sync was created to solve.  V-Sync On solves that problem, but it does so by ensuring that the GPU only sends a video frame when the display is ready to refresh.  The issue there is that it means the GPU has to sustain a frame rate at least as high as the display's refresh rate, i.e. with a 300 Hz display you'd need to sustain 300 fps, which is obviously a pretty tall order.  When the GPU's frame rate drops below the display's refresh rate, i.e. it doesn't have the next video frame ready for the display's next refresh cycle, then it will "buy time" by simply repeating the last frame -- which you perceive as stuttering or judder-y motion, and lag.  This is precisely the dilemma that G-Sync was created to solve.  It avoids frame tearing WITHOUT introducing the potential for this motion/lag issue by allowing the refresh rate of the display to adapt dynamically to the frame rate the GPU can sustain at any given time.  In that case, your display's refresh rate is its MAX refresh rate, not its fixed refresh rate, which removes the risk.  But if you don't have G-Sync, you don't have that option.

Gaming at "2K": First of all, "2K" is a bad term to use for display resolutions.  2K is technically a film resolution of 2048x1080, and therefore when applied in the consumer space it actually is SUPPOSED to refer to the nearest and slightly LOWER resolution of 1920x1080.  Similarly, "4K" is a film resolution of 4096x2160, but when used in the consumer space it refers to 3840x2160.  Somehow using 2K to refer to 2560x1440 came into vogue, but it's wrong, and the ambiguity about what a person actually means when they say "2K" can cause confusion that might lead people down the wrong path when troubleshooting something for example.  2560x1440 is rightfully called "QHD" or "1440p".  The former is only one extra character to type, but it adds a lot of disambiguation value.   In terms of whether 100 fps gaming at QHD is possible, it depends on the game and your detail settings.  But with modern games at detail settings you'd probably want to run, that would probably be a stretch for any gaming laptop, even a new M15 R3.  But you're also using FPS and Hz interchangeably in your question here.  The frame rate the GPU can achieve is not necessarily linked to the refresh rate of the signal it's sending to the attached display.  You're limited to 60 Hz at 4K resolution because that's what your display supports, because that's all HDMI 2.0 supports (same for DisplayPort 1.2).  But your GPU might still be able to render frames more quickly, or more slowly, depending on the complexity of what it's rendering.  Technologies like V-Sync and G-Sync determine how the rendered frames "map" onto refresh cycles of the display itself.

I don't know why you'd want a DP 1.4 to HDMI 2.0 for "the other display".  If you're getting a 240 Hz display, the overwhelming likelihood is that it will have a DisplayPort input.  It will probably be full-size DP rather than MiniDP, but in that case keep it simple and get a MiniDP to DP cable/adapter and call it a day.  There's no point adding active adapters into the mix when they're not needed.  That's just extra cost and complexity that is completely avoidable.

Being "capped" at 60 fps could be the result of using G-Sync or V-Sync.  If you have either of those, then the GPU won't render at a frame rat higher than the display's refresh rate.

Thanks, great read.

so in the quest for QHD  I followed the nvidia guide you posted and selected the ‘pc’ resolution and this allowed for 120hz, but today I’ve dropped a load of FPS and can’t figure out why.  I thought it was gsync so removed all of that, restored defaults in nvidia and also clicked on lowest settings in game and I’m hitting around 55 frames even though I’m on 1080p 120hz.......I might have to do a full system install to get back to original settings maybe.  At least I saw 100fps on ultra settings with rtx, I should have left it there I guess 

It’s a little temperamental, quite clearly in game you can’t get QHD more than 30hz, so far I’ve had full frames from 120hz and 60hz @4k.  Each time I change resolution or something it seems to mess up like when I return to 1080 it punishes me with low frames, I’ll try to fix again and then test gsync, wonder why QHD wont work....I did notice when I return to the desktop the screen is super tiny when at 4K and then really big at 1080, when the screen is the right size it tends to work so a clue there maybe

Quick update, so in the end my last attempt was to reboot the machine and boom things went back to normal so back in business!  Ultra settings with RTX on is hitting 100fps.....next I’ll try to enable gsync again and see what this does, although It’s so smooth I’m not sure the benefit.  I tried with or without vsync and can’t notice the difference. Actually I’ll test QHD out first to see how that goes, maybe get lucky with the frames this time.

Ok so back to the cable @jphughan  do you think the HDMI 2.0 cable I’m using is the reason I can’t get QHD at more than 30hz?  Odd it does 4K at 60hz.

I would have been happy with 1080 with hdr as that switches the colour depth from 8 bit to 12 bit and the illuminance really made a good impact BUT it halves the FPS down to 57!  I had read this was only a 10% performance cost not 50%

Gsync makes no impact to more/less frames, vsync scored the same too.  I’ve not tried vsync and gsync together, probably not wise.

There is a variable refresh option via the display options but would prefer steadier frames.  

The killer seemed to be clicking on fullscreen > exclusive fullscreen > 120 hz.......seems an obvious thing to enable but for reasons unknown it crashes the FPS down to like 30/40....thick this and then everything is back over 100 frames even though the greyed out option is stuck to 24hz, very misleading unless it needs to work with something else.

sorry to bombard....I know the result is in there

@Carl1978  It would have to be a pretty ancient HDMI cable to be limited to QHD at 30 Hz.  HDMI 2.0 would be able to handle QHD 120 Hz, and if it's running 4K 60 Hz, then the HDMI cable isn't there reason you only have QHD 30 Hz.  I'm guessing it's either GPU drivers or TV firmware, but I'm not sure since I don't have a lot of expertise in this particular area based on real world experience.  I'm just familiar with G-Sync as a technology.

You can't use G-Sync and V-Sync together.

Unless the variable refresh option in Windows somehow conflicts with G-Sync, variable refresh is absolutely something you want to use.  That's the entire point of G-Sync and HDMI VRR.  That doesn't destabilize your GPU's frame rate.  It allows your display's refresh rate to adapt to the frame rate fluctuations that the GPU will incur anyway as a result of the rendering complexity of its content changing from moment to moment.  If you keep your display's refresh rate static, then you have to either accept frame tearing or motion judder, as I already explained earlier.  Again, variable refresh rate in order to keep the display synced to the GPU's frame rate is the entire point of G-Sync.

Not sure about "exclusive full screen".

Did you already go through all of the steps outlined in the NVIDIA article I linked in my earlier post to make sure you'd set everything up exactly as specified?

I did follow the steps was handy but turns out I needed to change the power setting to Maximum, after this the 120hz option magically appeared in game!

Currently on QHD / RTX on / High settings hitting 80 FPS, pretty reasonable but my min aim is , just wondering how to get that extra.

Would you bother with the DP 1.4 to hdmi 2.0? 

also would you turn VRR and gsync in together?

cheers